If the Call Redirect step sends a caller to a device that does not exist in the CallManager, which branch of the step is executed? （）

A.DB Get  
B.DB Read  
C.DB Write  
D.DB Release

A.to release memory held by the prompt variable  
B.to clear the value of the menu choice before the prompt is played  
C.to prevent the previous value from being used again on the menu choice  
D.to prevent the caller from entering a menu choice before the prompt has played